Patient-specific acetabular guide and method

ABSTRACT

A method for inserting an acetabular cup into an acetabulum of a patient includes inspecting a preoperative plan including a three-dimensional image of a patient&#39;s acetabulum, selecting at least one of a patient-specific anteversion angle and a patient-specific abduction angle, and approving the preoperative plan. The method also includes preparing the patient&#39;s acetabulum for implantation, positioning a patient-specific first surface of an acetabular guide around a matched acetabular rim surface of the patient, and inserting an acetabular cup through an opening of the acetabular guide, the opening having a cylindrical inner surface oriented at the selected at least one of the patient-specific anteversion angle and patient-specific abduction angle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 12/389901, filed Feb. 20, 2009, which is: (A) a continuation-in-part of U.S. patent application Ser. No. 11/756057, filed on May 31, 2007, which claims the benefit of U.S. Provisional Application No. 60/812694, filed on Jun. 9, 2006; and (B) a continuation-in-part of U.S. patent application Ser. No. 12/211407, filed Sep. 16, 2008, which is a continuation-in-part of U.S. patent application Ser. No. 11/971390, filed on Jan. 9, 2008, now U.S. Pat. No. 8,070,752, issued on Dec. 6, 2011, which is a continuation-in-part of U.S. patent application Ser. No. 11/363548, filed on Feb. 27, 2006, now U.S. Pat. No. 7,780,672, issued on Aug. 24, 2010.

The disclosures of the above applications are incorporated herein by reference.

INTRODUCTION

Various custom made, patient-specific orthopedic implants and associated templates and guides are known in the art. Such implants and guides can be developed using commercially available software. Custom implant guides are used to accurately place pins, guide bone cuts, and insert implants during orthopedic procedures. The guides are made from a pre-operative plan formed from an MRI or CT scan of the patient and rely on matching a subcutaneous anatomic feature for correct positioning.

The present teachings provide a patient-specific guide for guiding an acetabular implant into the acetabulum.

SUMMARY

The present teachings provide an acetabular system. In one aspect, the acetabular system includes an acetabular guide having a first surface and a second surface opposite to the first surface, the first surface made to conform to an acetabular rim surface around an acetabulum of a patient in accordance with a three-dimensional image of the acetabulum of the patient. The acetabular guide includes an aperture having an inner surface oriented at selected anteversion and abduction angles relative to the first surface for guiding an acetabular implant into the acetabulum at the selected anteversion and abduction angles.

The present teachings also provide an acetabular system. The acetabular system includes an annular acetabular guide and an acetabular inserter. The acetabular guide includes a first surface and a second surface opposite to the first surface, the first surface being patient-specific and made to conform to an acetabular rim surface around an acetabulum of a patient in accordance with a three-dimensional image of the acetabulum of the patient. The acetabular guide has a cylindrical inner surface oriented at selected anteversion and abduction angles relative to the first surface. The acetabular inserter includes a guide-engaging portion with a cylindrical outer surface mateable with the cylindrical inner surface of the acetabular guide.

The present teachings also provide a method for inserting an acetabular cup into an acetabulum of a patient. The method includes inspecting a preoperative plan including a three-dimensional image of a patient's acetabulum, selecting at least one of a patient-specific anteversion angle and a patient-specific abduction angle, and approving the preoperative plan. The method also includes preparing the patient's acetabulum for implantation, positioning a patient-specific first surface of an acetabular guide around a matched acetabular rim surface of the patient, and inserting an acetabular cup through an opening of the acetabular guide, the opening having a cylindrical inner surface oriented at the selected at least one of the patient-specific anteversion angle and patient-specific abduction angle.

Further areas of applicability of the present teachings will become apparent from the description provided hereinafter. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present teachings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present teachings will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is an exemplary illustration of a patient in preparation of an acetabular implant procedure;

FIG. 1A is a perspective view of an acetabular guide according to the present teachings, the acetabular guide shown in relation to a patient's anatomy;

FIG. 2 is an environmental perspective view of the acetabular guide of FIG. 1A shown with an acetabular inserter holding an acetabular implant according to the present teachings;

FIG. 3 is a perspective view of the acetabular inserter and acetabular implant of FIG. 2;

FIG. 3A is a perspective environmental view of an acetabular implant illustrating rotation about an anatomic axis A during insertion according to the present teachings;

FIG. 3B is a perspective environmental view of an acetabular implant illustrating rotation about an anatomic axis B during insertion according to the present teachings; and

FIG. 4 is an exploded view of the acetabular inserter and acetabular implant of FIG. 3.

DESCRIPTION OF VARIOUS ASPECTS

The following description is merely exemplary in nature and is in no way intended to limit the present teachings, applications, or uses.

The present teachings generally provide a patient-specific acetabular guide and associated inserter for use in orthopedic surgery, such as in joint replacement or revision surgery, for example. The patient-specific alignment guides can be used either with conventional or patient-specific implant components prepared with computer-assisted image methods. Computer modeling for obtaining three dimensional images of the patient's anatomy using MRI or CT scans of the patient's anatomy, the patient-specific prosthesis components, and the patient-specific guides and templates can be provided by various CAD programs and/or software available, for example, by Materialise USA, Ann Arbor, Mich.

Patient-specific alignment guides and implants are generally configured to match the anatomy of a specific patient. The patient-specific alignment guides are generally formed using computer modeling based on the patient's 3-D anatomic image and have an engagement surface that is made to conformingly contact and match a three-dimensional image of the patient's bone surface (with or without cartilage or other soft tissue), by the computer methods discussed above. The patient-specific alignment guides can include custom-made guiding formations, such as, for example, guiding bores or cannulated guiding posts or cannulated guiding extensions or receptacles that can be used for supporting or guiding other instruments, such as drill guides, reamers, cutters, cutting guides and cutting blocks or for inserting pins or other fasteners according to a surgeon-approved pre-operative plan. The patient-specific alignment guides can be used in minimally invasive surgery, and in particular in surgery with multiple minimally-invasive incisions. Various alignment guides and preoperative planning procedures are disclosed in commonly assigned and co-pending U.S. patent application Ser. No. 11/756057, filed on May 31, 2007; U.S. patent application Ser. No. 12/211407, filed Sep. 16, 2008; U.S. patent application Ser. No. 11/971390, filed on Jan. 9, 2008, U.S. patent application Ser. No. 11/363548, filed on Feb. 27, 2006; and U.S. patent application Ser. No. 12/025414, filed Feb. 4, 2008. The disclosures of the above applications are incorporated herein by reference.

As disclosed, for example, in above-referenced U.S. patent application Ser. No. 11/756057, filed on May 31, 2007; in the preoperative planning stage for a joint replacement or revision procedure, an MRI scan or a series of CT scans of the relevant anatomy of the patient, such as, for example, the entire leg of the joint to be reconstructed, can be performed at a medical facility or doctor's office. The scan data obtained can be sent to a manufacturer. The scan data can be used to construct a three-dimensional image of the joint and provide an initial implant fitting and alignment in a computer file form or other computer representation. The initial implant fitting and alignment can be obtained using an alignment method, such as alignment protocols used by individual surgeons.

The outcome of the initial fitting is an initial surgical plan that can be printed or provided in electronic form with corresponding viewing software. The initial surgical plan can be surgeon-specific, when using surgeon-specific alignment protocols. The initial surgical plan, in a computer file form associated with interactive software, can be sent to the surgeon, or other medical practitioner, for review. The surgeon can incrementally manipulate the position of images of implant components in an interactive image of the joint. Additionally, the surgeon can select or modify resection planes, types of implants and orientations of implant insertion. For example, the surgeon may select patient-specific anteversion and abduction angles for acetabular implants, as discussed below. After the surgeon modifies and/or approves the surgical plan, the surgeon can send the final, approved plan to the manufacturer.

After the surgical plan is approved by the surgeon, patient-specific alignment guides can be developed using a CAD program or other imaging software, such as the software provided by Materialise, for example, according to the surgical plan. Computer instructions of tool paths for machining the patient-specific alignment guides can be generated and stored in a tool path data file. The tool path can be provided as input to a CNC mill or other automated machining system, and the alignment guides can be machined from polymer, ceramic, metal or other suitable material, and sterilized. The sterilized alignment guides can be shipped to the surgeon or medical facility, for use during the surgical procedure.

The present teachings provide a patient-specific acetabular guide and associated inserter for inserting an acetabular implant in the acetabulum of a patient's pelvis in a guided orientation at least about first and second non-parallel anatomic axes. Referring to FIGS. 1, 3A and 3B, the first anatomic axis indicated at “A”, passes through the acetabulum 82 of a patient's pelvis 80 (only half of the pelvis is shown) and is oriented generally in a superior/inferior direction relative to the patient. The second anatomic axis is indicated at “B” and is substantially perpendicular to the first axis A. As described below, the present teachings provide instruments and methods for guiding, orienting and positioning an acetabular implant 200 at a selected angle of anteversion relative to the axis A, as shown in FIG. 3A, and at a selected angle of abduction relative to the axis B, as also shown in FIG. 3B. The anteversion and abduction angles can be determined interactive or other surgeon input and can be patient-specific.

Referring to FIG. 1A, an exemplary acetabular guide 100 according to the present teachings can include a first surface 108 for engaging an area surrounding the acetabulum 82 and a second surface 110 opposite to the first surface 108. The acetabulum-engaging first surface 108 can be custom-made or patient-specific to conform and mirror an acetabular rim surface 84 around the acetabulum 82 of a specific patient by using three-dimensional image of the acetabulum and surrounding pelvic area of the patient, as described above. The first surface 108 enables the acetabular guide to nest or closely mate relative to the acetabulum 82 of the patient.

The acetabular guide 100 can be temporarily and removably attached to the pelvis 80 using temporary fasteners 120, such as bone nails or tacks, for example, passing through corresponding holes 104 through the acetabular guide 100. The acetabular guide 100 can be annular with an opening defined by an inner surface 102. The inner surface 102 can be, for example, a cylindrical surface. The inner surface 102 can be oriented relative to the first and second surfaces 108, 110 of the acetabular guide 100 to provide a selected anteversion angle about the first axis A and a selected abduction angle relative to the axis B, as shown in FIGS. 2, 3A and 3B. The anteversion and abduction angles can be surgeon-selected and patient-specific and can be determined with surgeon input during the preoperative planning for the specific patient. Anteversion angles can be, for example, in the range of about 10-20 degrees forward relative to the first axis A, and adduction angles can be in the range of about 40-50 degrees downward relative to the second axis B.

Referring to FIGS. 2-4, the acetabular guide 100 can be attached to the pelvis 80 around the acetabulum 72 after the acetabulum 82 has been reamed and prepared for receiving the acetabular implant 200, such as the Magnum™ acetabular cup commercially available from Biomet, Inc., Warsaw, Ind. The acetabular implant 200 can be inserted into the prepared acetabulum 82 using an inserter 300 according to the present teachings. The inserter 300, which can also function as an impactor, can include a handle 304 with a proximal impaction surface 318, a shaft 302 and a guide-engaging portion 310 having a surface with a flat or planar portion 320. The guide-engaging portion 310 can have an outer surface 312, which conforms to and is mateable with the inner surface 102 of the acetabular guide 100 for guiding the acetabular implant 200. The inner surface 102 and the outer surface 312 can be cylindrical.

Referring to FIG. 4, the inserter 300 can engage the acetabular implant 200 via an intermediate member 250, such as the intermediate member of the Magnum™ system, which is commercially available from Biomet, Inc., Warsaw, Ind. More specifically, the inserter 300 can include a distal portion 314, such as a ball-bearing bushing, which can be inserted and engage a receptacle 252 of the intermediate member 250. The acetabular implant 200 can be mounted on the inserter 300 by aligning a plurality of fingers 254 of the intermediate member 250 with corresponding cut-outs 202 on a peripheral edge of the acetabular implant 200. The acetabular implant 200 can be secured to the inserter 300 by rotating the acetabular implant 200 relative to the insert 300 until a hand-tight fit is obtained.

Referring to FIG. 2, the inserter 300 with the acetabular implant 200 mounted thereon can be directed toward the acetabular guide 100. The outer surface 312 of the guide engaging portion 310 of the inserter 300 can be brought into contact with the inner surface 102 of the acetabular guide 100, guiding the acetabular implant 200 toward the selected anteversion and abduction orientation through the acetabular guide 100. The outer surface 312 of the guide engaging portion 310 can also provide an impaction-depth feedback by alignment with the inner surface 102 of the acetabular guide. Full impaction of the acetabular implant 200 into the acetabulum 82 can be indicated when planar portion 320 and/or outer surface 312 of the guide-engaging portion 310 of the inserter 300 are flush with and do not protrude over and above the second surface 110 of the acetabular guide 100. Depth indicia 322 can also be provided on the inserter shaft 302 or on the guide-engaging portion 310 of the inserter 300, as shown in FIG. 2.

After the acetabular implant 200 is fully seated in the acetabulum 82 in the selected anteversion and abduction orientations, the inserter 300 and intermediate member 250 can be removed. The temporary fasteners 120 can be removed and the acetabular guide released.

The acetabular guide 100 can be made of any biocompatible material, such as metal, ceramic or polymer. The acetabular guide 100 can be constructed by various manufacturing methods depending of the selected material, including, for example, machining, casting, molding, stereolithography or other layer deposition methods. In one aspect, the acetabular guide 100 can be made of disposable plastic material.

The foregoing discussion discloses and describes merely exemplary arrangements of the present teachings. Furthermore, the mixing and matching of features, elements and/or functions between various embodiments is expressly contemplated herein, so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one embodiment may be incorporated into another embodiment as appropriate, unless described otherwise above. Moreover, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the present teachings as defined in the following claims. 

1. A method for inserting an acetabular cup into an acetabulum of a patient, the method comprising: inspecting a preoperative plan including a three-dimensional image of a patient's acetabulum; selecting at least one of a patient-specific anteversion angle and a patient-specific abduction angle; approving the preoperative plan; preparing the patient's acetabulum for implantation; positioning a patient-specific first surface of an acetabular guide around a matched acetabular rim surface of the patient, the first surface configured as a mirror surface of the acetabular rim surface; and inserting an acetabular cup through an opening of the acetabular guide, the opening having a cylindrical inner surface oriented at the selected at least one of patient-specific anteversion and patient-specific abduction angle.
 2. The method of claim 1, wherein inserting an acetabular cup through an opening of the acetabular guide comprises: mounting the acetabular cup on an acetabular inserter; contacting a cylindrical outer surface of the acetabular inserter to the cylindrical inner surface of the acetabular guide, the cylindrical outer surface of the acetabular inserter matching the cylindrical inner surface of the acetabular guide; impacting the acetabular inserter; and seating the acetabular cup to the acetabulum at the selected anteversion and abduction angles.
 3. The method of claim 2, further comprising determining a depth of impaction of the acetabular cup.
 4. The method of claim 3, wherein determining a depth of impaction of the acetabular cup includes aligning a flat portion of the acetabular inserter relative to the first surface of the acetabular guide.
 5. A method for inserting an acetabular cup into an acetabulum of a patient, the method comprising: positioning a first surface of an acetabular guide around an acetabular rim surface of an acetabulum of the patient, the first surface preoperatively configured as a mirror surface of the acetabular rim surface of the patient from a three-dimensional image of the acetabulum of the patient, the acetabular guide including an aperture having an inner surface oriented at preoperatively determined and patient-specific anteversion and abduction angles relative to the first surface; coupling an acetabular cup to a distal portion of an acetabular inserter; contacting an outer surface of a guide-engaging portion of the acetabular inserter to the inner surface of the acetabular guide, the outer surface preoperatively configured to mate with the inner surface at the patient-specific anteversion and abduction angles; and seating the acetabular cup to the acetabulum at the selected anteversion and abduction angles.
 6. The method of claim 5, further comprising: impacting the acetabular inserter.
 7. The method of claim 6, further comprising: determining a depth of impaction of the acetabular cup.
 8. The method of claim 7, wherein determining the depth of impaction of the acetabular cup includes aligning a planar portion of the guide-engaging portion of the acetabular inserter relative to the first surface of the acetabular guide.
 9. The method of claim 7, wherein determining the depth of impaction of the acetabular cup includes impacting the acetabular inserter to a depth determined by depth indicia marked on the acetabular inserter.
 10. The method of claim 9, wherein the depth indicia are provided on the guide-engaging portion of the acetabular inserter.
 11. The method of claim 5, wherein coupling the acetabular cup to the distal portion of the acetabular inserter includes rotating the acetabular cup relative to the inserter.
 12. The method of claim 5, wherein coupling the acetabular cup to the distal portion of the acetabular inserter includes aligning a plurality of fingers of an intermediate member with corresponding cut-outs on a peripheral edge of the acetabular cup.
 13. The method of claim 12, further comprising engaging a receptacle of the intermediate member with a bushing of the acetabular inserter.
 14. The method of claim 6, wherein impacting the acetabular inserter includes impacting a proximal impaction surface of a handle of the acetabular inserter.
 15. The method of claim 5, wherein the inner surface of the acetabular guide and the outer surface of the guide-engaging portion of the acetabular inserter are cylindrical.
 16. A method for inserting an acetabular cup into an acetabulum of a patient, the method comprising: coupling a distal portion of an acetabular inserter to an intermediate member; connecting an acetabular cup to the intermediate member; positioning a first surface of an acetabular guide around an acetabular rim surface of an acetabulum of the patient, the first surface preoperatively configured as a mirror surface of the acetabular rim surface of the patient from a three-dimensional image of the acetabulum of the patient, the acetabular guide including an aperture having an inner surface oriented at preoperatively determined and patient-specific anteversion and abduction angles relative to the first surface; mateably contacting an outer surface of a guide-engaging portion of the acetabular inserter to the inner surface of the acetabular guide at the patient-specific anteversion and abduction angles; and inserting the acetabular cup into the acetabulum at the selected anteversion and abduction angles.
 17. The method of claim 16, further comprising: impacting a proximal impaction surface of the acetabular inserter to a predetermined depth by aligning a planar portion of the guide-engaging portion of the acetabular inserter relative to the first surface of the acetabular guide
 18. The method of claim 16, further comprising coupling a bushing of the acetabular inserter to a receptacle of the intermediate member.
 19. The method of claim 16, further comprising aligning a plurality of fingers of the intermediate member with corresponding cut-outs on a peripheral edge of the acetabular cup.
 20. The method of claim 16, further comprising impacting a proximal impaction surface of the acetabular inserter to a depth determined by depth indicia on the guide-engaging portion of the acetabular inserter. 